This application relates generally to injection molding apparatus and more particularly to a one-piece gate and cavity insert formed of three components which are integrally joined together.
Injection molding apparatus having gate and cavity inserts with cooling fluid flow passages which form a portion of the cavity and through which the gate extends to convey melt from a heated nozzle through the cavity are well known. For example, U.S. Pat. No. 4,622,001 to Bright et al. which issued Nov. 11, 1986 shows a gate and cavity insert made of two separate pieces which are bolted together. More recently, U.S. Pat. No. 5,443,381 to Gellert which issued Aug. 22, 1995 shows a one-piece gate and cavity insert formed of inner and outer components or portions which are integrally joined together with a cooling fluid flow passage extending therethrough. The outer component is made of a suitable steel such as H13 or stainless steel, while the inner component is made of a beryllium-nickel alloy which is more heat conductive and corrosion resistant.
While these previous configurations are satisfactory for many applications, it has been found that there is excessive wear in the gate area when molding certain materials under certain conditions.